1. Technical Field of the Invention
This invention relates generally to electric motors and more particularly to stators.
2. Description of Related Art
As is known, there are various types of electric motors and an almost endless variety of uses for them. For instances, an electric motor may be an AC motor (e.g., synchronous or induction), a servo motor, a DC motor, or an electrostatic motor (e.g., magnetic motor) and may be used in applications that range from micro-mechanical systems (MEMS), to food processing equipment, to household appliances, to power tools, to automobiles, to toys, to large manufacturing equipment, etc. Basically any device that uses mechanical motion includes an electric motor.
Due to the vast uses of electric motors, they come in an almost endless variety of sizes, shapes, and power levels. For instance, the size of a MEMS motor is small enough to fit on an integrated circuit and supplies nano-watts of power, while a large manufacturing equipment motor may be tens of feet in diameter supplying hundreds of thousands of kilowatts of power. Note that power of electric motors is sometimes expressed in horsepower, where one horsepower equals 746 watts.
Regardless of the type, size, shape, and power level, an electric motor includes a stator and a rotor. The stator includes coils that produce a magnetic field, which causes motion of the rotor (e.g., its output shaft rotates). For radial flux motors, the stator produces a radial flux (e.g., spreading out from the center); while stators of axial flux motors typically produce an axial flux (e.g., located along the plane of the axis).
While a motor contains two primary components (e.g., the stator and the rotor), the manufacturing of a motor is far from a simple process. For instance, manufacturing a DC brushless pancake motor (e.g., a motor whose width is greater than its axial length) requires the development of tooling to produce the components of the motor and/or to assemble the components of the motor. Further, the manufacturing steps of producing the motor can be quite expensive. For instance, a back iron of the stator is fabricated to include mechanical fittings to hold the stator poles in place, which requires special tooling to produce. Then, in manufacturing, the stator poles are physically pressed into the mechanically fittings, which must be done in an identical manner to prevent variations in the mechanically coupling.
For certain applications (e.g., less than 10 horsepower), the cost of tooling and manufacturing has severely limited the production of economical pancake brushless DC (BLDC) motors. Therefore, a need exists for a stator and method of manufacture thereof to produce pancake DC motors and other axial flux motors.